In the prior art, the use of reactors or vessels in which a thermal interaction or thermal exchange between materials takes place is well known. Such reactors may be of the type in which particulate material is introduced, and a gas having a different temperature than that of the particulate material is directed to pass through the particulate material so that a thermal interaction takes place between the particulate material and the gas. This type of thermal interaction is referred to as countercurrent flow and is described in detail in U.S. Pat. No. 3,876,383.
In the prior art, it is also known to place two of such heat-exchange reactors in relation to each other so that the particulate material, after it is heated by a waste gas or fluid in one reactor, is transferred to the second reactor, where the particulate material gives up its heat to a working fluid. However, there are a number of drawbacks with such an arrangement.
More particularly, the temperature of the waste gas supplied to the first reactor typically varies and is not useful to impart heat energy to the particulate material until the waste gas reaches a sufficient temperature. However, during the time that the incoming waste gas is not of a sufficiently high temperature, heated particulate material cannot be supplied to the second reactor to heat the working fluid in that reactor. As a result, in such arrangements, a continuous supply of heated working fluid cannot be provided. In addition, in such prior art arrangements, all of the hot waste gases are drawn into the first reactor to heat the particulate material, even though, at certain times, only a portion of such waste gases may be required to meet the demands of the system. It would therefore be desirable to provide a system wherein a continuous supply of heated working fluid is provided and a system wherein only that part of the waste gases are utilized which are required to meet the demands of the system so that any remaining hot waste gases which are not utilized in the first reactor can be used for another purpose.
Accordingly, it is an object of the present invention to provide an improved system which overcomes the aforesaid problems. Specifically, it is within the contemplation of the present invention to provide a system which utilizes an incoming hot gas having a varying temperature to store heat energy and to transfer same, as needed, to a working fluid to maintain the working fluid at a substantially constant temperature.
It is a further object of the present invention to provide a waste heat recovery and storage system which uses only that portion of the incoming hot waste gas required to meet the demands of the system to maintain the working fluid at a constant temperature, so that the unused hot incoming gas may be utilized for another purpose, such as being supplied to another heat exchanger.
It is a still further object of the present invention to provide a waste heat recovery system wherein a portion of the incoming hot waste gases is supplied to a first heat exchanger, and the remaining hot waste gases are supplied to a second heat exchanger in parallel with the first heat exchanger, so that each of the parallel heat exchangers receives the hot waste gases at substantially the same temperatures.
It is a still further object of the present invention to provide a waste heat recovery system wherein the reactor receiving the hot waste gases and its peripheral equipment does not have to withstand high temperatures, since unneeded and unused hot waste gases are supplied to a parallel heat exchanger.
It is a still further object of the present invention to provide a waste heat recovery system wherein the working fluid heated by the particulate material can have additional heat energy supplied to it by the use of additional heaters or burners.